1. Chapter 3
What Do Samples Tell Us?

2. From Sample to Population 1
A purchaser for a large convenience store chain wants to know if the shipment of 1,000,000 batteries he is receiving is a good one. He randomly selects 100 batteries from the shipment and tests their charge. Two of the batteries did not have a full charge.
Identify the parameter.
A. 1,000,000 batteries in the shipment
B. 100 randomly selected batteries
C. 2% = the percent of the 100 selected batteries that do not have a full charge
D. percent of the 1,000,000 batteries that do not have a full charge

3. From Sample to Population 1 (answer)
A purchaser for a large convenience store chain wants to know if the shipment of 1,000,000 batteries he is receiving is a good one. He randomly selects 100 batteries from the shipment and tests their charge. Two of the batteries did not have a full charge.
Identify the parameter.
A. 1,000,000 batteries in the shipment
B. 100 randomly selected batteries
C. 2% = the percent of the 100 selected batteries that do not have a full charge
D. percent of the 1,000,000 batteries that do not have a full charge (correct)

4. From Sample to Population 2
A purchaser for a large convenience store chain wants to know if the shipment of 1,000,000 batteries he is receiving is a good one. He randomly selects 100 batteries from the shipment and tests their charge. Two of the batteries did not have a full charge.
Identify the statistic.
A. 1,000,000 batteries in the shipment
B. 100 randomly selected batteries
C. 2% = the percent of the 100 selected batteries that do not have a full charge
D. percent of the 1,000,000 batteries that do not have a full charge

5. From Sample to Population 2 (answer)
A purchaser for a large convenience store chain wants to know if the shipment of 1,000,000 batteries he is receiving is a good one. He randomly selects 100 batteries from the shipment and tests their charge. Two of the batteries did not have a full charge.
Identify the statistic.
A. 1,000,000 batteries in the shipment
B. 100 randomly selected batteries
C. 2% = the percent of the 100 selected batteries that do not have a full charge (correct)
D. percent of the 1,000,000 batteries that do not have a full charge

6. From Sample to Population 3
A recent Pew Research poll asked 1060 parents of 13–17 year olds whether they use parental controls for blocking, filtering, or monitoring their teen’s online activity. 413 said they did.
Find the observed proportion (the sample proportion), p , of those who use parental controls.
A) B) C)
D) E)

7. From Sample to Population 3 (answer)
A recent Pew Research poll asked 1060 parents of 13–17 year olds whether they use parental controls for blocking, filtering, or monitoring their teen’s online activity. 413 said they did.
Find the observed proportion (the sample proportion), p , of those who use parental controls.
A) B) 𝟒𝟏𝟑 𝟏𝟎𝟔𝟎 (correct) C)
D) E)

8. From Sample to Population 4
The observed proportion, p , of parents who use parental controls is a
sample
statistic
population
parameter

9. From Sample to Population 4 (answer)
The observed proportion, p , of parents who use parental controls is a
sample
statistic (correct)
population
parameter

10. Sampling Variability 1 A parameter is
known and will not vary from sample to sample
unknown and will not vary from sample to sample
known and will vary from sample to sample
unknown and will vary from sample to sample

11. Sampling Variability 1 (answer)
A parameter is
known and will not vary from sample to sample
unknown and will not vary from sample to sample (correct)
known and will vary from sample to sample
unknown and will vary from sample to sample

12. Sampling Variability 2 A statistic is
known and will not vary from sample to sample
unknown and will not vary from sample to sample
known and will vary from sample to sample
unknown and will vary from sample to sample

13. Sampling Variability 2 (answer)
A statistic is
known and will not vary from sample to sample
unknown and will not vary from sample to sample
known and will vary from sample to sample (correct)
unknown and will vary from sample to sample

14. Sampling Variability 3
The observed proportion, p , of parents who use parental controls will
be the same from sample to sample
be different from sample to sample
be unknown

15. Sampling Variability 3 (answer)
The observed proportion, p , of parents who use parental controls will
be the same from sample to sample
be different from sample to sample (correct)
be unknown

16. Sampling Variability 4 In a study, it is most important to reduce bias
reduce variability
reduce both bias and variability
use random sampling

17. Sampling Variability 4 (answer)
In a study, it is most important to
reduce bias
reduce variability
reduce both bias and variability (correct)
use random sampling

18. Sampling Variability 5 In order to reduce bias, one should
take a smaller sample size
take a larger sample size
be sure to use the best random sampling scheme

19. Sampling Variability 5 (answer)
In order to reduce bias, one should
take a smaller sample size
take a larger sample size
be sure to use the best random sampling scheme (correct)

20. Sampling Variability 6 In order to reduce variability, one should
take a smaller sample size
take a larger sample size
be sure to use the best random sampling scheme

21. Sampling Variability 6 (answer)
In order to reduce variability, one should
take a smaller sample size
take a larger sample size (correct)
be sure to use the best random sampling scheme

22. Margin of Error and All That 1
Computing the margin of error when using a statistic to estimate a parameter is
quantifying the bias
telling us what sample size to use
quantifying how much the statistic would vary from sample to sample
quantifying how much the parameter would vary from sample to sample

23. Margin of Error and All That 1 (answer)
Computing the margin of error when using a statistic to estimate a parameter is
quantifying the bias
telling us what sample size to use
quantifying how much the statistic would vary from sample to sample (correct)
quantifying how much the parameter would vary from sample to sample

24. Margin of Error and All That 2
Using a larger sample size
increases margin of error
decreases margin of error
has no effect on margin of error

25. Margin of Error and All That 2 (answer)
Using a larger sample size
increases margin of error
decreases margin of error (correct)
has no effect on margin of error

26. Margin of Error and All That 3
A recent Pew Research poll asked 1060 parents of 13–17 year olds whether they use parental controls for blocking, filtering, or monitoring their teen’s online activity.
Using the quick formula, compute the margin of error for 95% confidence.
A) B) C)
D) E)

27. Margin of Error and All That 3 (answer)
A recent Pew Research poll asked 1060 parents of 13–17 year olds whether they use parental controls for blocking, filtering, or monitoring their teen’s online activity.
Using the quick formula, compute the margin of error for 95% confidence.
A) B) C)
D) 𝟏 𝟏𝟎𝟔𝟎 (correct) E)

28. Confidence Statements
A poll of 1,000 recent college grads revealed 9.6% believe Judith Sheindlin (Judge Judy) is on the Supreme Court. Suppose the MOE is 3% and the resulting confidence interval is (6.6,12.6).
Choose the correct confidence statement.
We are 95% confident that between 6.6 and 12.6% of recent college graduates think Judge Judy is on the Supreme Court.
We are 95% confident that between 6.6 and 12.6% of recent college graduates sampled think Judge Judy is on the Supreme Court.

29. Confidence Statements (answer)
A poll of 1,000 recent college grads revealed 9.6% believe Judith Sheindlin (Judge Judy) is on the Supreme Court. Suppose the MOE is 3% and the resulting confidence interval is (6.6,12.6).
Choose the correct confidence statement.
We are 95% confident that between 6.6 and 12.6% of recent college graduates think Judge Judy is on the Supreme Court. (correct)
We are 95% confident that between 6.6 and 12.6% of recent college graduates sampled think Judge Judy is on the Supreme Court.

30. Sampling from Large Populations
A simple random sample of size, n = 150, was taken from a population of size 250,000. Another simple random sample of size, n = 150, was taken from a population of size of 100,000.
Which sample will yield a statistic with less variability?
The first SRS will have less variability since the population is larger.
The second SRS will have less variability since the population size is smaller.
The variability will be similar since the sample sizes are the same.

31. Sampling from Large Populations (answer)
A simple random sample of size, n = 150, was taken from a population of size 250,000. Another simple random sample of size, n = 150, was taken from a population of size of 100,000.
Which sample will yield a statistic with less variability?
The first SRS will have less variability since the population is larger.
The second SRS will have less variability since the population size is smaller.
The variability will be similar since the sample sizes are the same. (correct)